tricking someone into revealing the truth; fishing for information
Refers to a tactic of pretending ignorance or making a misleading statement to get someone to confirm or disclose something. Often used in the phrase 鎌をかける.
See also: かまをかける
He drew out the other person's true feelings with a trick question.
People who are good at fishing for information naturally gather it during conversation.
Literally 'sickle hooking'. The expression likely comes from the image of using a sickle to hook something and pull it out, metaphorically applied to extracting hidden information. The exact origin is uncertain.